Re: [PATCH v5 02/17] iommu/arm-smmu-v3: Consolidate the STE generation for abort/bypass

Will Deacon
2024-02-22T17:40:59Z

On Thu, Feb 15, 2024 at 05:27:09PM +0000, Robin Murphy wrote:
> On 06/02/2024 3:12 pm, Jason Gunthorpe wrote:
> > +/*
> > + * This can safely directly manipulate the STE memory without a sync sequence
> > + * because the STE table has not been installed in the SMMU yet.
> > + */
> > static void arm_smmu_init_bypass_stes(struct arm_smmu_ste *strtab,
>
> This name is long out-of-date - if we're refreshing this area, please rename
> to something relevant to what it actually does, e.g. s/bypass/initial/.
>
> Although frankly I also think that at this point we should just get rid of
> the disable_bypass parameter altogether - it's been almost entirely
> meaningless since default domain support was added, and any tenuous cases
> for wanting inital STEs to be bypass should probably be using RMRs now
> anyway.

We probably can't drop it for SMMUv2, but I'd be more than happy to do so
on SMMUv3. I think one of the reasons for keeping it in the new driver was
that the Arm Fast Model used to need it for legacy virtio devices that were
downsteam of the SMMU but couldn't advertise F_ACCESS_PLATFORM. Was that
fixed?

Will